Turquoise hydrogen via multi-pass FCCVD turns methane into clean hydrogen and high-value carbon nanotube materials—slashing waste and opening new green markets.
Why turning methane into materials changes the decarbonization math
Hydrogen today is a climate problem as much as it’s a solution. Producing ~100 million tonnes of H₂ per year is responsible for roughly 2–3% of global greenhouse gas emissions. At the same time, steel and concrete alone account for over 10% of global emissions. Most companies treat these as two separate headaches: decarbonize fuels over here, decarbonize materials over there.
Here’s the thing about methane pyrolysis and turquoise hydrogen: it attacks both problems at once.
A new study published in late 2025 shows a multi-pass floating catalyst chemical vapour deposition (FCCVD) reactor that converts methane into:
- High-purity hydrogen (up to ~85% in the raw stream)
- Structural carbon nanotube (CNT) mats and fibers
with no CO₂ coming out of the reactor and ~99% of process gas recycled internally. For anyone building green technology roadmaps or hydrogen strategies, this is a very different proposition from standard “blue” or “green” hydrogen.
This article breaks down what this technology actually does, why it matters for decarbonization, and how businesses should be thinking about it in 2026 planning cycles.
From burning methane to upgrading it: how turquoise hydrogen works
Turquoise hydrogen comes from methane pyrolysis—splitting methane (CH₄) into hydrogen and solid carbon instead of burning it into CO₂.
The core reaction is simple:
CH₄ (gas) → C (solid) + 2 H₂ (gas)
The reaction is endothermic: you have to put heat in. But it’s less energy-intensive than water electrolysis and even lower than steam methane reforming per unit of hydrogen produced. The key difference is what happens to the carbon:
- Steam methane reforming (SMR): carbon leaves as CO₂
- Electrolysis: you avoid fossil carbon, but pay a high electricity price
- Methane pyrolysis: carbon leaves as a solid material that you can sell or store
This matters because:
- If you use fossil natural gas, you get low-CO₂ hydrogen as long as you control upstream methane leaks.
- If you use biogas or landfill gas, you can be net CO₂-negative: carbon captured by plants ends up locked into CNT-based materials instead of going back to the atmosphere.
The multi-pass FCCVD system described in the paper is especially interesting because it’s a “carbon-first” hydrogen technology. Instead of making low-value carbon powders, it makes high-performance CNT mats and fibers with:
- Tensile strengths already reaching >8 GPa in 2024 research fibers
- Electrical conductivities around 5 MS/m in advanced CNT fibers
- Very low density (~1–2 g/cm³ at the tube level)
In other words, this isn’t just about clean fuel. It’s about creating next-generation structural materials that can displace steel, aluminum, copper, and carbon black.
Inside the multi-pass FCCVD reactor: why recycling gas is a big deal
Most FCCVD CNT reactors today are single-pass: feed in methane + hydrogen + catalysts, get CNT aerogel out, vent a huge waste gas stream containing unreacted methane and hydrogen. That’s fine for lab work, but terrible for process efficiency and hydrogen production.
The multi-pass FCCVD reactor changes this by turning the reactor into a quasi-closed loop:
- About 99% of the process gas is recycled through the hot reaction zone multiple times.
- Fresh methane and catalyst (ferrocene + thiophene) are “topped up” in small amounts before each pass.
- CNT aerogel (a continuous web of CNTs) is wound onto a roller as a mat or fiber.
- Hydrogen-rich gas is continuously extracted as an effluent stream.
What this does for efficiency
On a lab scale, switching from single-pass to multi-pass FCCVD achieved:
- 33× reduction in waste/product mass ratio (from 99:1 down to 3:1)
- 8.7× increase in carbon yield (fraction of carbon ending up in CNTs)
- ~446× increase in overall molar process efficiency when you count hydrogen as a product
- No exogenous hydrogen supply needed in steady state — recycled hydrogen does the job
Put differently: single-pass labs were effectively converting ~0.1% of input atoms into useful product. The multi-pass setup lifts that to ~45% when hydrogen is included.
For green technology strategists, this is crucial. It shifts FCCVD from “beautiful but wasteful lab toy” into something that starts to look like an industrially relevant reactor concept.
Biogas compatibility and carbon-negativity
The researchers also tested the multi-pass reactor with 33% CO₂ mixed into the methane, mimicking raw biogas or landfill gas. Performance dropped somewhat:
- CNT production down ~25%
- Efficiency lower than with pure methane
But even with CO₂ in the feed, the process still delivered:
- ~4× higher carbon yield
- ~32× higher molar carbon efficiency
relative to the single-pass baseline. CO₂ does react with solid carbon to form CO (a loss pathway), but the system still works. That’s important if you’re looking at waste-to-value projects or municipal biogas upgrading.
Scaling up: from lab reactor to pilot plant economics
Lab reactors are great for proofs of concept, but they don’t convince CFOs. The study did something more useful: it took real data from a pilot-scale single-pass FCCVD plant and modelled what happens if you convert it to multi-pass.
Pilot single-pass performance (real data)
A commercial pilot reactor (operated by an industrial CNT producer) showed:
- 30 g/h CNT output
- Volumetric productivity: ~3.4 kg CNT per m³ of reactor per hour
- Carbon yield: ~60%
That’s already much better than lab single-pass systems, but the process still vents a huge hydrogen-rich off-gas. Essentially, it’s throwing away the hydrogen you just paid to produce.
Modelled pilot multi-pass performance
Applying the multi-pass logic to that same scale, the study projects:
- 75% of mass throughput becomes useful product
- 3:1 mass ratio of CNTs to hydrogen
- Hydrogen productivity: ~1.1 kg H₂/m³·h
- Hydrogen production efficiency: ~88%
- 57× higher molar process efficiency vs. pilot single-pass
For context, this moves FCCVD into the performance range of established fluidized-bed methane pyrolysis in terms of hydrogen productivity, while maintaining superior carbon quality.
In practical business terms:
- You’re no longer just paying for a fancy way to make CNTs.
- You’re running a dual-product plant: a structural carbon factory and a low-CO₂ hydrogen plant sharing the same core assets.
Carbon powders vs structural CNTs: why product form matters
Most methane pyrolysis research today is “hydrogen-first.” You get decent turquoise hydrogen and a low-value carbon byproduct:
- Carbon black-like powders
- Large-diameter CNT powders with low Raman quality (I_G/I_D ~1)
The global carbon black market is ~18 million tonnes per year, while meeting today’s hydrogen demand via pyrolysis would generate ~300 million tonnes of solid carbon per year. That mismatch is huge.
If we treat carbon as waste or low-grade filler, turquoise hydrogen hits a market wall long before it replaces fossil fuels.
The FCCVD multi-pass approach flips the logic:
- It’s carbon-first: the default output is a macroscopic CNT mat or fiber, not a loose powder.
- CNTs are small-diameter (~10 nm) and high quality (lab dilute recipes reached Raman I_G/I_D ≈ 6, comparable to CNT fibers that recently achieved ~8–14 GPa strength).
- The material can be densified and processed into:
- Lightweight structural fibers and tapes
- Reinforcement for polymers and concrete
- High-conductivity conductors and busbars
- Advanced battery and supercapacitor additives
This is exactly the kind of carbon you can deploy at steel-scale volumes, because it competes in large material markets:
- Steel: ~1.6 billion tonnes per year
- Aluminum, copper, reinforcing fibers, and composites: hundreds of millions of tonnes combined
If even a small fraction of those markets shift to CNT-based materials produced from methane, you:
- Create a serious sink for solid carbon from turquoise hydrogen.
- Displace CO₂-intensive metals and cement, multiplying the climate benefit.
From a green technology portfolio perspective, that’s the kind of stacking effect you want: one process, multiple decarbonization levers.
What this means for companies planning hydrogen and materials strategy
If you’re working on hydrogen, industrial decarbonization, or green technology investment, here are concrete implications.
1. Treat turquoise hydrogen as a materials decision, not just a fuel decision
Choosing methane pyrolysis vs. electrolysis isn’t just about CAPEX, OPEX, and CO₂ per kg H₂. It’s also about what kind of carbon product you’re locked into:
- Fluidized beds, molten metals, thermal cracking: great for bulk hydrogen, give you powders and low-grade carbons.
- Multi-pass FCCVD: lower methane concentration, but higher-value CNT mats and fibers.
If your business touches construction, mobility, electronics, or energy storage, the carbon product could be worth more than the hydrogen in the long run.
2. Look for integrated projects with biogas and waste streams
The study showed the reactor can run on methane contaminated with ~33% CO₂, mimicking raw biogas or landfill gas. That opens up interesting project configurations:
- Waste operator or municipality supplies unrefined biogas.
- Turquoise hydrogen plant converts it to low-CO₂ hydrogen + CNT materials.
- Solid CNTs lock in atmospheric carbon; H₂ fuels transport or industrial heat.
That’s effectively bioenergy with carbon capture and storage (BECCS) – except the “storage” is valuable structural material, not a cost center.
3. Don’t underestimate the engineering challenges
The paper is optimistic but honest about what still needs work:
- Carbon losses: even at pilot scale, ~15% of carbon still ends up as deposits and unusable solids. That’s got to come down by orders of magnitude at megatonne scale.
- Catalyst consumption: ferrocene and thiophene currently run at ~25% and 7.5% of methane mass at pilot scale. That’s not acceptable at commodity scale without big gains in catalyst efficiency or a switch to cheaper elemental precursors.
- Leakage management: methane leaks upstream and hydrogen leaks downstream both have real warming impacts. Any serious deployment must include rigorous leak detection and repair.
That said, the direction of travel is clear: multi-pass FCCVD turns a niche CNT process into a credible building block for green industry.
Where this fits in the Green Technology landscape
Seen alongside electrolysis, SMR+CCS, and plasma pyrolysis, multi-pass FCCVD isn’t “the one true hydrogen solution.” But it fills a specific, high-value niche in the green technology stack:
- It’s ideal for regions with stranded natural gas or biogas and strong advanced manufacturing ecosystems.
- It aligns with smart cities and sustainable infrastructure that need lighter, stronger, more conductive materials for grids, transit, and buildings.
- It offers a pathway to scale CNT production to megatonnes (Huntsman has publicly talked about 1 Mt/year CNT ambitions), with roughly 330 kt/year of co-produced hydrogen per such plant.
Most companies get hydrogen strategy wrong by treating it as a stand-alone energy product. The reality? Hydrogen is tightly coupled to materials, infrastructure, and feedstock choices. Processes like multi-pass FCCVD make that coupling explicit.
If you’re planning your next phase of decarbonization:
- Map where turquoise hydrogen with high-value solid carbon outperforms both blue and green hydrogen on a system basis.
- Talk to your materials, R&D, and infrastructure teams at the same time as your energy team.
- Start small with pilot projects that integrate hydrogen supply, CNT-based materials use, and biogas or waste methane streams.
The next wave of green technology won’t just replace fossil fuels with clean energy. It will rebuild the material backbone of the economy—and turning methane into both clean hydrogen and super-materials is one of the more elegant ways to get there.